Elevator systems have proven useful for carrying passengers between different levels in buildings. A variety of different elevator system configurations are available. Traction-based elevator systems include a roping arrangement that supports the weight of the elevator car and a counterweight. A machine drives a traction sheave that causes movement of the roping members to cause desired movement of the elevator car.
Various roping arrangements are known in the industry. The most straightforward is considered a 1:1 roping arrangement in which the movement of the roping members and the corresponding amount of movement of the elevator car is the same. In a 2:1 roping arrangement the roping members movement is twice as much as the corresponding movement of the elevator car. 4:1 roping arrangements have been proposed and include roping member movement that is approximately four times as much as the corresponding movement of the elevator car.
With the introduction of flat belt suspension members in place of round steel ropes, the ability to realize different roping arrangements is more complicated. The U.S. Patent Application Publication No. US 2008/0121468 shows one possible 4:1 roping arrangement that includes flat belts as the roping members. That document proposes an arrangement that includes a stacked arrangement of deflection sheaves on one side of the hoistway. One disadvantage associated with such an arrangement is that it requires more vertical space within the hoistway to accommodate the arrangement of those sheaves. Minimizing the amount of hoistway space required for an elevator system is an ongoing challenge within the elevator industry.